温度对充血性心衰病人心房肌细胞I_(to)和I_(Kur)的影响

Contributions of temperatures to I_(to) and I_(Kur) in human atrial myocytes isolated from patients with congestive heart failure

运用全细胞膜片钳技术研究不同温度条件下充血性心衰病人心房肌细胞瞬间外向钾电流（I_（to））和超快延迟整流钾电流（I_（Kur））的特征。结果表明：在5~9和16~20℃2种不同的温度下,I_（to）、I_（Kur）存在着明显不同的激活、失活等动力学特征。当环境温度较低时,引导出Ito、IKur所需的电压阈值较低,半数最大激活电位较低,电流-电压之间的关系较恒定,除极至＋50 mV时的电流密度较小。但Ito的电压依赖性失活过程却不受温度的影响。就时间依赖性动力学过程而言,温度较低时通道的激活时间常数和失活时间常数的数值较小,时间-电位间的关系不随电位的变化而发生明显的改变;温度较高时,激活时间常数和失活时间常数的数值较大,且随着刺激电位的增高,激活时间常数和失活时间常数变得越来越小。说明温度对充血性心衰病人Ito、IKur的大小和动力学特征具有明显影响。

To study the characteristics of transient outward K~＋current（Ito） and ultra-rapid delayed rectifier K＋current（IKur at different temperature in congestive heart failure（CHF）patients,Ito）and IKurwere recorded using whole-cell patch clamp technique.The Results showed that Ito and IKur had distinct activation or inactivation kinetic properties at different temperature.Compared with higher temperature,the activating thresholds of Itoand Ikurat lower temperature were lower,and the half-maximal activation potentials of Ito and IKur were smaller,however their Current-voltage relationships were not changed.The current densities of Ito were smaller when depolarized to ＋50 mV,and that of IKur were smaller either under identical voltage.But the voltage-dependent inactivation of Ito was not affected by temperature.Activation time constants or inactivation time constants of Ito were smaller at lower temperature,and the relationships of timevoltage were not modified obviously.However,they became greater when temperature rose,and decreased when potential increased.We could draw a conclusion from this experiment that Ito and IKurhad different properties at 5—9℃and16-20℃.